They will ask you about your background. What fields in Oral medicine you are most interested in - medically compromised, pain, lesions, etc. they will what to know if you plan to go into education and if you would want to complete the entire program (more than 1 year).
You may wish to ask about on-call, research, required projects(papers/ research/ etc).
Each program is different. the education will be based on the attendings.